Solar Panels and batteries that could recharge an Aptera?

[plateauhops]

Hello, I just recently joined this forum and have been doing some research into Lithium Phosphate batteries for solar energy storage and home production which is interesting and from what I gather still not very ready except for a few custom builds. My question is regarding the A123 batteries that are used in the Aptera's 20kwh battery pack. I picked the Aptera because of it's aerodynamic nature and low weight, and am thinking it would be one of the electric cars that would require the fewest solar battery needs, yet could possibly be one of the first manageable cars to be powered under a moderate amount of solar panels.This is all just speculation.

I was thinking of asking this in that electric car forum mentioned here, but wasn't sure if solar is a sub-topic. Nonetheless, I might check there to ask questions about the BMS that can be quite challenging. So, has anyone tried to recharge an Aptera or other electric car using an all-solar panel setup? If I commuted every day with an an Aptera 20 miles (10 miles each way) and, assuming it has at least an 80 mile range, would it lose about 5kwh a day, and if I had a 10kwh solar setup just for charging the car (or having a larger one) and on the yearly minimum I got about 5kwh a day, would it be enough to recharge from 75% to 100% (15kwh back up to 20kwh) overnight so the car battery doesn't deplete over the week? I think this would require 2 battery setups, one for collecting solar energy during the day (since the car might not be at home during the weekday, but rather, at an office), and then when the car comes home, the home batteries could transfer DC-DC or use an inverter inefficiently to charge the Aptera's internal batteries overnight from storage. I don't prefer to swap them, as that would be inconvenient as it's not designed that way. I'm kind of fascinated by the thought that solar could replace the gasoline, electric, and heat too. Another car I was considering was the Zap Xebra electric, but it doesn't seem as rangeful as the Aptera.

[plateauhops]

oops I noticed the Volt uses a 16kwh pack, so I could use that as an example too, even though I'm interested in more range, and I think I would get more miles/Kwh performance in the Aptera, which would require less charging I think. For example the Volt has a range form 25-50miles, meaning the 16kwh might be depleted 8k~14kwh just to drive 20 miles. So that's why I chose the Aptera, as I might get 100 miles+ and still use it during the week by partially recharging it then and possibly having the weekend day hours (since it might be at home more often then) to fill up whatever wasn't charged during the week.

[Sunking]

So, has anyone tried to recharge an Aptera or other electric car using an all-solar panel setup?

I will try to be short. It cannot be done. Well can't be justified economically to recharge it entirely on solar alone.

Best solution is just to install a regular grid tied system at your home to offset the charger use or as much of your energy needs as you think you can afford. In addition when that is installed you can have the electrician wire you up a 240 dedicated outlet for the class 2 charger that is offered.

The problem with doing what you want to do is you would have to build a stand alone system with a huge conventional lead acid battery bank. At replacing 10 Kwh into the EV would require you to store 20 Kwh every day, and at least a 50 Kwh lead acid battery bank to transfer into the EV. It is just not feasible and could easily cost you around $50,000 or more to do it with a stand alone battery system.

Just do the math, buy it from the POCO at 12 cents per Kwh, so for 10 Kwh cost you a $1.20 per day. How many days does it take to break even at $50K initial investment plus $15,000 every 5 or so years replacing the lead acid batteries in the stand alone system. Well here is some quick numbers. 5 years buying at 12-cents per Kwh will cost you $.12 x 10 Kwh per day x x 1825 days = $2190 fuel bill from the electric company. If it cost you $50K to do it with stand alone battery, you will be paying $50,000 / (10 Kwh per day x 1825 days0 = $2.74 per Kwh. So in this example you just volunteered to pay 2.74 / .12 = 22 times more than you pay now for electricity. Can I sign you up please?

The real solution to gasoline light vehicle fleet is EV's powered by nuclear power plants.

[plateauhops]

I will try to be short. It cannot be done. Well can't be justified economically to recharge it entirely on solar alone.

Best solution is just to install a regular grid tied system at your home to offset the charger use or as much of your energy needs as you think you can afford. In addition when that is installed you can have the electrician wire you up a 240 dedicated outlet for the class 2 charger that is offered.

The problem with doing what you want to do is you would have to build a stand alone system with a huge conventional lead acid battery bank. At replacing 10 Kwh into the EV would require you to store 20 Kwh every day, and at least a 50 Kwh lead acid battery bank to transfer into the EV. It is just not feasible and could easily cost you around $50,000 or more to do it with a stand alone battery system.

Just do the math, buy it from the POCO at 12 cents per Kwh, so for 10 Kwh cost you a $1.20 per day. How many days does it take to break even at $50K initial investment plus $15,000 every 5 or so years replacing the lead acid batteries in the stand alone system. Well here is some quick numbers. 5 years buying at 12-cents per Kwh will cost you $.12 x 10 Kwh per day x x 1825 days = $2190 fuel bill from the electric company. If it cost you $50K to do it with stand alone battery, you will be paying $50,000 / (10 Kwh per day x 1825 days0 = $2.74 per Kwh. So in this example you just volunteered to pay 2.74 / .12 = 22 times more than you pay now for electricity. Can I sign you up please?

The real solution to gasoline light vehicle fleet is EV's powered by nuclear power plants.

Thanks for your reply. It's an interesting curiosity and I wouldn't be able to afford it at the moment, but if I didn't need to drive every day and instead if it was something I used just for groceries/errands every two weeks, then I am still optimistic about the possibility that I could charge it 1kwh a day for 10 days, collecting 2 kwh a day, and using a 5kwh battery storage for example, by using a smaller system. I'm not sure how much a full charge loses every day- might it be more than 1%? If i only used it once every two weeks and drove less than 4 miles, then I think it could be a neat place to start. I agree it'd still cost more than the grid but maybe not 22x, but rather 2.2-4x? Also, I would buy batteries that last at least 10 years, and I prefer batteries that don't require venting- sealed or life-po4. Again, thanks for the realistic current estimates.

[Sunking]

The problem is without adding on an additional charger to the car, or some other modification your idea would not work. The vehicles internal charger minimum power requirement must be met, or else it shuts down.

Example. Assuming the on board controller is 120 VAC house power 20 amp circuit, the internal charger will charge with what is known as a constant current. It takes the 120 VAC and charges the battery with a constant current. Using the Nissian Leaf as an example because I am familiar with it, will charge at 50 amps @ 390 volts. That equates to 200 watts. If your power AC power source cannot provide that power level, the charger will see that as a fault and shut down.

[plateauhops]

Using the Nissian Leaf as an example because I am familiar with it, will charge at 50 amps @ 390 volts. That equates to 200 watts. If your power AC power source cannot provide that power level, the charger will see that as a fault and shut down.

Aptera
# 110v 15A charge time: 8 hrs
# Battery output: 10-13 Kw/hr battery pack
# Battery voltage: 336V DC Nominal Traction Voltage

I wasn't able to find the 220v+ ones.

As much as I'd like to avoid using an inverter due to the loss of efficiency, it probably will benefit me out of convenience. Would a pure sine wave inverter with a continuous & surge charge above 200 watts mean it would be capable?

For example:
Magnum MS2012 2000 watt
pure sine wave inverter/charger

[Sunking]

Aptera
# 110v 15A charge time: 8 hrs
# Battery output: 10-13 Kw/hr battery pack
# Battery voltage: 336V DC Nominal Traction Voltage

I wasn't able to find the 220v+ ones.

The aptera has a 240 VAC port to allow full recharge of the 21 Kwh battery in 3 to 4 hours

Not sure, but I like the idea that I'd charge it on 110v.

Not sure why you would prefer the 120 VAC charging port. Assuming the 21 Kwh battery was fully discharge it would take roughly 12 to 14 hours, where as at 240 VAC it takes roughly 3 to 4 hours.

Over the course of the day maybe I could get 1kwh (with enough PVs) storage (?), and then if I needed to charge it at 200watts (as in the Leaf case), it could charge for 5 hours...unless it doesn't work that way.

OK I must not have explained it good enough the first time around. You cannot charge it at 200 watts using the vehicle charger. The Aptera charger needs to have a full 2000 watts input at 120 VAC 15 amps. If not the charger will shut down and stop.

Your best bet is like I said earlier. Install a grid tied system on your home and all those headaches go away.

[plateauhops]

The aptera has a 240 VAC port to allow full recharge of the 21 Kwh battery in 3 to 4 hours


Not sure why you would prefer the 120 VAC charging port. Assuming the 21 Kwh battery was fully discharge it would take roughly 12 to 14 hours, where as at 240 VAC it takes roughly 3 to 4 hours.


OK I must not have explained it good enough the first time around. You cannot charge it at 200 watts using the vehicle charger. The Aptera charger needs to have a full 2000 watts input at 120 VAC 15 amps. If not the charger will shut down and stop.

Your best bet is like I said earlier. Install a grid tied system on your home and all those headaches go away.

Ah Ok. So Watts= Volts x Amps --> 120VACx15amps= 1800 watts, or 2000, as you say. The surge capacity is 3300 watts, but I think that means I'd only be able to charge it for one hour if I had a fullly charged 2kwh battery pack, though I know I might need more than 2000 watts. And I'd need 12-14 hours...I only picked 120VAC since I didn't expect batteries today to be made for high voltage drains.

I know a grid-tie is the best solution. I was just exploring a theory where I could try out a piecemeal, long-term summing of recharging, IF I maintained a routine of using it only once every two weeks. So I'd need at least a 12kwh battery pack (probably more) to charge it for 5 hours at 2000watts/hr each day. My goal is to partially charge it the way I'd charge a laptop from 40% to 50%. If, for example, it takes an hour to charge a laptop in 10% increments, and I only had 1 hour a day to charge it an additional 10%, I'd keep it completely off every day until it was fully charged, taking into account battery losses of 1-3%. So after the 11th day, I could turn the laptop on and would estimate it to be 94-99% charged. Thus I was describing something like a slow rice cooker, in reverse...if that makes any sense. Again, just a theory, not something I'm going to invest in in the near future.

[Sunking]

Ah Ok. So Watts= Volts x Amps --> 120VACx15amps= 1800 watts, or 2000, as you say. The surge capacity is 3300 watts, but I think that means I'd only be able to charge it for one hour if I had a fullly charged 2kwh battery pack, though I know I might need more than 2000 watts. And I'd need 12-14 hours...I only picked 120VAC since I didn't expect batteries today to be made for high voltage drains.

Correct Power = Volts x Amps = EI.
Standard 120 VAc circuits in a residential home are either 15 or 20 amps maximum capacity. So I am guessing a bit on what the Aptera charger is doing. For continuous loads like a charger, the manufacture cannot draw full load current, only 80%. So if the charger is designed for a 15 amp circuit, then 120 V x 15 amps x .8 = 1440 watts, or 120 x 20 x .8 = 1920 watts. But that is on the AC side, and does not account for the charger and battery charge efficiency. So once at the battery could be as low as 1 Kw on a 15 amp circuit, up to 1.5 Kw on a 20 amp circuit. So if you needed to replace 5 Kwh could take as long as 5 to 6 hours.

The only way you could charge directly with a solar panel in the fashion you want is to completely redesign the vehicles internal charger and BMS. Otherwise you have to supply the demands of the internal charger for as long as it needs it or it will just shut down.

[plateauhops]

Here's what I've gathered from another forum, where someone gave me pointers on insolation at Overclockers (my username is Xenohitsu there)

"For Chicago, your kWh/m2/day (insolation) for December is 2.27. 4 fixed-mount panels at 225W w/ an 80% battery efficiency factor = (.9KW*2.27) * .8 = 1.6KW/H per day.

Keep in mind that this is under ideal circumstances; i.e., nothing blocking the full view of rising and setting sun and the ideal angle of 55 degrees south (Winter angle). Days with heavy clouds will result in significantly lower output."

http://www.overclockers.com/forums/showthread.php?t=658215

So I'd need eight 225w panels to get 3.2kw/h /day in ideal winter circumstances. If I had a cloudy day, I think I'd get less than 2kw. I read someone here gets 2kwh minimum on the darkest winter conditions, I forget who, but am curious how many PVs that requires-14-16?. I know it's expensive since the only batteries that would be capable of nearly full depletion every day would be batteries with 5,000-10,000 cycles, and I've read elsewhere on this forum that 10Amp draws gives 4,000 cycles on another battery model whereas 30Amps I think results in fewer cycles, like 1,500. So that's another reason I don't want to use that many amps, no more than 15 or 20, to maximize the number of cycles, and at least 5,000 would be nice. On the Aptera's draw/charge efficiency, I'm not sure how that works but it would be cool if it had two charge options, using DC and AC plugs, which I'd agree would need to redesign much of it. Though, if I had to use the inverter, the above is one idea.

Edit: I just noticed that a Sol-man, for example will only "run 800 to 1000 watts all day, and 400 watts all night", so I wouldn't use that particular model if it can't draw more than 1920 watts continuously (whether it's 1 hour, 5, or more), though again, I probably got something else wrong (not in reference to getting two examples mixed up- the above link began with PSUs and another thought about how to heat a small building/home, and then I was examining other systems for cars).

Also, this setup would rely on having the batteries be charged everyday from as much solar collection as possible, then in the evening, whatever the batteries have collected, would be transferred to the Aptera for 1 hour, 5, etc. Then the next day it would repeat, till the charge goes to full.

[Sunking]

No offense but you are so confused I do not know where to start.

You are still assuming you can hook up a panel to the EV and charge it. YOU CANNOT DO THAT unless you gut the vehicles whole internal charger and BMS and replace it with one that can work with a solar panel array. The internal charger is made to work with AC power without any limitations of power input level. I guess that is the place to start.

[plateauhops]

The internal charger is made to work with AC power without any limitations of power input level.

Ok, that's what I was wondering about.

I can see where you might have thought I was confused, but I wasn't saying I would connect the solar panels directly to the EV. I only acknowledged that I'd need an inverter for AC and inquired what all the accompanying requirements might be, as I'm not sure if it has ever been tested. In other words, how is residential 120Vac different from AC from an inverter, if all amperage, battery, etc requirements are fulfilled?

For example, on the first page you said:
"Example. Assuming the on board controller is 120 VAC house power 20 amp circuit, the internal charger will charge with what is known as a constant current. It takes the 120 VAC and charges the battery with a constant current. Using the Nissian Leaf as an example because I am familiar with it, will charge at 50 amps @ 390 volts. That equates to 200 watts. If your power AC power source cannot provide that power level, the charger will see that as a fault and shut down."

Then I pointed out the:

Magnum MS2012 2000 watt
pure sine wave inverter/charger
• surges to 3300 watts
• continuous charge at 100 amps

Is "constant current" as you described the same as "continuous charge" listed above? And, if so, additionally, using the Aptera, which needs 15amps of "constant current", would a 100amp inverter/charger that can handle 100amps of continuous charge be able to recharge the Aptera if it only needs 15 amps, is my question. Thanks.

Then I acknowledged that the internal battery in the EV isn't designed for DC, but it would be *cool* if it were, and understand it would require it to be gutted and reconfigured, but that's a whole other discussion that I'm not ready to get into. That's all.

[Sunking]

I can see where you might have thought this, but I wasn't saying I would connect the solar panels directly to the EV. I only acknowledged that I'd need an inverter for AC and inquired what all the accompanying requirements might be, as I'm not sure if it has ever been tested. In other words, how is residential 120Vac different from AC from an inverter, if all amperage requirements are fulfilled?

The difference is a household AC circuit supplied by the utility is unlimited power practically speaking. You can connect the commercial AC power to a 1500 watt load device and it delivers 1500 watts until you quit paying for it or turn it off.

There are two ways to use an inverter: Grid Tied, and Battery

1. Use a grid tied system. The commercial AC power makes up for what the solar panel cannot deliver.

2 Build one heck of a large and very expensive stand alone off grid battery system with an additional set of very large batteries to charge your EV... It has not been tested because once you understand the economics you realize it is a huge waste of money and resources. Not too mention the GREEN POLICE will prosecute you and ask for the death penalty.

[plateauhops]

That sums it up pretty much.

[Sunking]

When and If EV's become mainstream I can easily see manufactures offering an OPTIONAL charge port for a Renewable Energy source like Solar or Wind Turbine. But that is well off into the future, well beyond most of our life times left on earth.

I do see EV's in the next 20 years becoming mainstream with all the money being poured in from both private and public sectors for battery development as it is the best and viable method to replace ICE transportation for the light vehicle market. The big question is where will the electric power generation come from. Right now the answer is inexpensive, clean and safe nuclear power for the next 1000 years. There is no answer for medium and heavy transportation except fossil or food crop fuels.